SPLIT SYSTEM INSTALLATION (cont’d)
Installing the Evaporator Unit
Please refer to the supplied Unit Specific Installation Guide
for detailed evaporator installation guidelines.
Head Pressure Control, Low Ambient Control Switch, Fan Cycling Switch:
These switches are used to cycle the condenser fan at low ambient temperature conditions. If your unit is equipped with a Low Ambient Control, set the switch to 170 psig for
Refrigeration Lines
A 1/4 inch O/D copper “liquid line” and a 3/8 or 1/2 inch O/D copper “suction line” connect the two units.
The refrigerant drier and the sight glass shall be installed (in that order) in the direction of the refrigerant flow in the liquid line between the condensing unit and evaporator. Enclose the suction line in a cellular insulation ½” wall thickness Armaflex (brand name) or equal to reduce heat transfer.
Wiring System
The compressor is controlled by a “pump down cycle,” therefore, no wiring between the condensing unit and evaporator unit is necessary. Wire the system in accordance with local codes and the enclosed wiring diagrams (pg 22). The evaporator unit requires a standard 20 amp circuit,
Charging the System (by Certified HVAC technician)
After all the piping is complete:
Open both of the service valves on the condensing unit (the unit is pressurized with nitrogen, and there should be an audible sound of gas escaping through the service ports).
With electrical power connected to the evaporator unit, energize the solenoid valve (pressurize with dry nitrogen) to 200psi. Leak test all fittings. The system must hold 200psi for 30 minutes.
If no leaks are found, leave the solenoid valve energized and evacuate the system through both the liquid and suction service ports. Using a high vacuum pump, evacuate to 200 microns, measuring the vacuum with a digital micron gauge. When evacuation is complete, break vacuum and pressurize with liquid
With the electrical power turned on to the condensing unit, and the evaporator unit running, slowly feed liquid refrigerant (R134A) into the suction service port. As the suction pressure rises to 15 PSIG, the condens- ing unit will start. Slowly feed refrigerant while maintaining a pressure above 10 PSIG to prevent the com- pressor from short cycling. Slowly feed refrigerant with the compressor running until the sight glass is clear of all bubbles. Do not exceed 3.5 lbs of refrigerant. Check superheat at the evaporator outlet. Superheat should be at
Allow the system to operate for one hour and then check the refrigerant level in the sight glass again. Ad- ditional refrigerant may be required as the temperature of the enclosure is lowered to approximately 55°F or the ambient temperature at the condensing unit rises above the temperature at which the unit was initially charged. Depending on temperature, the “high side” should be approximately 175 lbs, and the ”low side” 28 lbs or more to keep the evaporator from icing. It is recommended while charging to use a digital refrigerant scale for better accuracy in measuring the amount of charge.
Page 8 |
